1. Unit 4: Sensation and Perception
CHS AP Psychology
Unit 4: Sensation and Perception
Logo Green is R=8 G=138 B= Blue is R= 0 G=110 B=184
Border Grey is R=74 G=69 B=64
Essential Task 4.6: Discuss how experience, context and culture can influence perceptual processes with specific attention to perceptual set, illusions, change blindness, and selective attention.

2. What do we perceive then?
Subliminal Threshold
When energy of the stimulus is below one’s absolute threshold for conscious awareness.
What do we perceive then?

3. Subliminal Perception Sensation without perception?
Subliminal = stimuli that sensory system responds to, but due to short duration or subtle form, don’t reach threshold of cognition
Quick Survey
Do you think you are influenced by subliminal messages in advertising?
Do you think you are influenced by everyday advertisements that you perceive consciously (e.g. laundry detergent, beverages)?

4. We are not obedient to Subliminal Messages
Research shows that the effect only occurs in controlled laboratory studies for a short time. When flashed words to elicit these moods we see slightly:
More competitive participants
More critical participants
More supportive
Research outside the laboratory shows no significant effect of subliminal information
We don’t blindly obey!
Placebo Effect with subliminal self help tapes

5. Perceptual Set Activity

6. Group A
You are going to look briefly at a picture and then answer some questions about it.
The picture is a rough sketch of a poster for a costume ball. Do not dwell on the picture. Look at it only long enough to “take it all in” once.
After this, you will answer YES or NO to a series of questions.

7. Group B
You are going to look briefly at a picture and then answer some questions about it.
The picture is a rough sketch of a poster for a trained seal act. Do not dwell on the picture. Look at it only long enough to “take it all in” once.
After this, you will answer YES or NO to a series of questions.

8. Picture

9. In the picture was there . .
A car?
A man?
A woman?
A child?
An animal?
A whip?
A sword?
A man’s hat?
A ball?
A fish?

10. Conclusion
Top Down processing – you go beyond the sensory information to try to make meaning out of ambiguity in your world
What you expect (your experiences and your perceptual set) drives this process
Today we will see what expectations we all have in common.

11. Perceptual Set
A mental predisposition to perceive one thing and not another. What you see in the center picture is influenced by flanking pictures.
Preview Question 23: How do our expectations, contexts, and emotions influence our perceptions?
From Shepard, 1990.

12. Perceptual Set Other examples of perceptual set.
Frank Searle, photo Adams/ Corbis-Sygma
Dick Ruhl
(a) Loch ness monster or a tree trunk; (b) Flying saucers or clouds?

13. Context Effects Context can radically alter perception.
Is the “magician cabinet” on the floor or hanging from the ceiling?

14. Context instilled by culture also alters perception.
Cultural Context
Context instilled by culture also alters perception.
To an East African, the woman sitting is balancing a metal box on her head, while the family is sitting under a tree.

15. Work on Vocabulary! 

16. Extrasensory Perception
Refers to extraordinary perception such as
Clairvoyance – awareness of an unknown object or event
Telepathy – knowledge of someone else’s thoughts or feelings
Precognition – foreknowledge of future events
Research has been unable to conclusively demonstrate the existence of ESP